NMP can be utilized in various chemical processes. For example, NMP is used as a reactant, chemical reaction medium, recrystallization medium, or a cleaning agent. NMP is often used as a chemical reaction medium since it has excellent heat and chemical stability.
In particular, NMP can be used in the production of poly(arylene sulfide), hereinafter referred to as P(AS). Generally, to produce P(AS), at least one halogenated aromatic compound, at least one sulfur source, and NMP are contacted under polymerization conditions. During the production of P(AS), at least one contaminant selected from the group consisting of phenol, thiophenol and phenyl disulfide can be generated producing a contaminated NMP. If the contaminated NMP is utilized in a subsequent polymerization, the P(AS) produced can have a significant reduction in molecular weight compared to P(AS) produced with uncontaminated NMP.
In addition, phenol, thiophenol and phenyl disulfide are difficult to separate from contaminated NMP. Distillation of the contaminated NMP is not sufficient to separate the phenol, thiophenol and phenyl disulfide from the NMP.
Polyhalogenated aromatic compounds have been utilized to remove thiophenol and phenyl disulfide from NMP. However, after an uncontaminated NMP is recovered, various compounds remain including unreacted aryl halides, which can cause a waste disposal problem.
There is a need in the industry to provide an efficient process to remove at least one contaminant from contaminated NMP that does not create waste disposal problems. This invention provides such a process.